As first you need elementary SDK
sudo apt install elementary-sdk
Install dependencies
sudo apt install libgtksourceview-3.0-dev graphviz
Clone repository and change directory
git clone https://github.com/artemanufrij/graphui.git
cd graphui
Compile, install and start GraphUI on your system
meson build --prefix=/usr
cd build
sudo ninja install
com.github.artemanufrij.graphui